Pressure-sensitive phthalide compound copying sheet

ABSTRACT

WHEREIN R1, R2, R3, R4, X, Y AND N ARE DESCRIBED HEREINAFTER, IS DISCLOSED.   (Y)N-ISOBENZOFURAN-1-ONE   3-(2-X,4-(R1-N(-R2)-)-PHENYL),3-(1-R3,2-R4-INDOL-2-YL),   A PRESSURE-SENSITIVE COPYING SHEET COMPRISING AN ADSORBENT SOLID ACID AND A MICROENCAPSULATED COLOR FORMER CAPABLE OF FORMING A DISTINCT COLOR WHEN REACTED WITH SAID ADSORBENT SOLID ACID COATED ON THE SAME OR DIFFERENT SURFACE OF SUPPORT OR SUPPORTS, SAID MICROCAPSULES CONTAINING AN ORGANIC SOLVENT HAVING DISSOLVED THEREIN AS A COLOR FORMER AT LEAST ONE PHTHALIDE COMPOUND REPRESENTED BY THE FOLLOWING FORMULA:

UnitedStates Patent 3,829,322 PRESSURE-SENSITIVE PHTHALIDE COMPOUNDCOPYING SHEET Minoru Ozntsumi, Yoshihide Miyazawa, and KatsuichiMotohashi, Tokyo, and Masataka Kiritani, Shizuoka, Japan, assignors toHodogaya Chemical Co., Ltd., Tokyo, and Fuji Photo Film Co., Ltd.,Kanagawa, Ja an Ni Drawing. Filed Dec. 23, 1971, Ser. No. 211,757

Claims priority, application Japan, Dec. 28, 1970,

Int. Cl. B41m /22 US. Cl. 117--36.8 5 Claims ABSTRACT OF THE DISCLOSUREA pressure-sensitive copying sheet comprising an adsorbent solid acidand a microencapsulated color former capable of forming a distinct colorwhen reacted with said adsorbent solid acid coated on the same ordifferent surface of support or supports, said microcapsules containingan organic solvent having dissolved therein as a color former at leastone phthalide compound represented by the following formula:

wherein R R R R X, Y and n. are described hereinafter, is disclosed.

BACKGROUND OF 'THE INVENTION 1. Field of the Invention The presentinvention relates to a pressure-sensitive copying paper, moreparticularly to a pressure-sensitive copying paper having a microcapsulelayer containing a novel phthalide compound as a color former.

2. Description of the Prior Art Pressure-sensitive copying papersgenerally comprise a transfer sheet having thereon a layer of finecapsules containing therein a solution of an electron donating colorlessorganic compound (hereinafter the organic compound is called the colorformer) in an organic solvent, and a receiving sheet, having thereon alayer of an electron-accepting solid. A suitable binder is usuallypresent to contain the solid.

When both sheets are put together such that the electron donating layeris brought into contact with the electron accepting layer, and localpressure is applied to the combination by handwriting or typewriting,the capsules are ruptured and the colorless color former contained inthe capsules is adsorbed on the electron accepting solid, usually asolid acid, to form the color.

Pressure-sensitive copying paper systems are also known which consist ofthe aforesaid transfer sheet (hereinafter this sheet is called the uppersheet) and a receiving sheet (hereinafter this sheet is called the lowersheet) and an intermediate sheet (hereinafter this sheet is called themiddle sheet). In these systems the middle sheet usually has coated, onopposite surfaces, a layer of microcapsules containing the color formersolution and a layer of the solid acid and a binder.

As another embodiment of pressure-sensitive copying systems, there is arecording sheet which may be prepared 2' by coating the above describedmicrocapsu'les and the absorbent solid acid on the same surface ofafsupport.

As the electron accepting solid material, solid acids are usually used,e.g. acid clay, attapulgite, zeolite, bentonite, kaolin, acid polymerssuch as phenolic resin and the like. Illustrative organic solvents fordissol-w'ng the color former are ethylene glycol, chlorobenzene, andchlorodiphenyl.

In general, Crystal Violet Lactone has widely been used as apurple-color former. Although Crystal Violet Lactone is immediatelycolored purple-blue when it is brought into contact with anelectron-accepting solid acid, it suffers from the followingdisadvantages: the color exhibits poor light fastness and thepurple-blue vanishes upon contact with water.

Benzoyl Leuco Methylene Blue has also been used as a blue-color former.When the color former is brought into contact with an electron acceptingsolid acid, a blue color having good light fastness is formed but thiscolor former has the disadvantage that it takes a long period of time tocolor.

To partially overcome the above disadvantages a mixture of these colorformers has been used. However, for the reasons mentioned above thecolor formed on pressure-sensitive copying papers using the mixture ofthese color formers changes gradually from purple-blue to blue and todark blue with the passage of time.

Recently, pressure-sensitive copying sheets in which anindole-substituted phthalide compound is used as the color former weredisclosed by Chao-Han Lin and Dayton in US. Pat. No. 3,540,911. However,the compounds described in the specification of this patent have thefollowing disadvantages: the color density of the color obtained by thecontact thereof with an electron-accepting solid acid is not high andthe colored compound exhibits weak water resistance.

SUMMARY OF THE INVENTION According to the present invention, there isprovided a pressure-sensitive copying paper containing as a color formerthe phthalide compound represented by the general formula I wherein Rrepresents a hydrogen atom, a methyl group, an ethyl group, an acetylgroup, or a benzyl group; R represents a methyl group, or an ethylgroup; R represents a hydrogen atom, a methyl group, or an ethyl group;R represents a methyl group, or a phenyl group; X represents a methylgroup, methoxy group, or an ethoxy group; Y represents a hydrogen atom,a chlorine atom, a bromine atom, or a dimethylamino group; and n is aninteger from 1 to 4. I

DETAILED DESCRIPTION OF THE INVENTION An object of the present inventionis, therefore, to provide pressure-sensitive copying papers containingas a color former the phthalide compound represented by the aforesaidgeneral formula which is immediately colored when it is brought intocontact with a solid acid to provide a stable purple or blue colorhaving excellent light fastness and water resistance.

An object of this invention is to provide pressure-sensitive copyingpapers which can be colored various colors by using the phthalidecompound represented by the afore- I GO OH X I R1\ I R2 R4 Yn a COOH OHR Thus, the phthalide compound used in this invention represented by thegeneral formula described above may be prepared by reacting thecorresponding benzophenone carboxylic acid and an indole or thecorresponding benzoylindole and an aromatic amine for 1-10 hours at areaction temperature of 50130 C., in the presence of a condensing agentsuch as acetic anhydride or phosphorus oxychloride using, if necessary,a volatile inert organic solvent such as benzene, or chloro-benzene,pouring the reaction mixture in ice-cooled water or a dilute aqueoussolution of an acid such as hydrochloric acid to hydrolyze thecondensing agent, adding a volatile inert solvent such as benzene orchlorobenzene to extract the product, alkalizing the reaction mixturewith an aqueous solution of a basic material such as sodium hydroxide,recovering the solvent layer, and distilling away the solvent therefromunder reduced pressure.

Examples of producing such phthalide compounds used in this inventionwill be explained below in detail.

PRODUCTION EXAMPLE 1 A mixture of 2.0 g. of1,2-dimethyl-3-(2'-carboxybenzoyl)-indole, 1.6 g. ofN,N-diethyl-m-toluidine, and 14.3 g. of acetic anhydride was heated to50-55 C. for hours, with stirring, to cause the reaction. The reactionmixture was poured in 400 g. of ice-water to hydrolyze the aceticanhydride, and after adding thereto 100 g. of benzene, the pH of themixture was adjusted to 12 by adding an aqueous solution of sodiumhydroxide. The benzene layer formed was recovered by decantation andafter treating the benzene layer with activated carbon, benzene wasdistilled off under reduced pressure. Then, by recrystallizing theresidue from petroleum ether, 2.0 g. of 3-(2-methyl-4'-diethylaminophenyl) 3 (1',2'-dimethylindol- 3-yl)-phthaliderepresented by the following formula was obtained as a white colorformer having a melting point of 180-182 C. When a benzene solution ofthe color former thus prepared was brought into contact with an acid clay layer coated on a paper; the color former immediately colored blue. j

PRODUCTION EXAMPLE 2 0 0 115 C2H5 I N C 1 I CzHs O\ OH: I

as a white color former having a melting point of 215- 216 C. When abenzene solution of the color former was brought into contact withan'acid clay layer coated on a paper, the color former immediatelycolored violetblue.

PRODUCTION-EXAMPLE 3 To 15 g. of monochlorobenzene were added 2.0 g. of1,2-dimethyl-3-(2'-carboxybenzoyl)-indole and 1.1 g. ofN-methyl-m-anisidine and then 1.6 g. of phosphorus oxychloride wasfurther added to the mixture.

The resultant mixture was heated to -105 C. for 2 hours with stirring tocause the reaction. The reaction mixture was poured in 400 g. ofice-waterto hydrolyze the phosphorus oxychloride, and after addingthereto 100 g. of monochlorobenzene, the pH of the mixture was adjustedto 12 by adding an aqueous solution of sodium hydroxide. Themonochlorobenzene layer formed was recovered by decantation and aftertreating the monochlorobenzene layer with activated carbon,monochlorobenzene was distilled oil under reduced pressure. Then, byrecrytallizing the residue from petroleum ether, 1.6 g. of 3(2'-methoxy-4'-methylaminophenyl)-3(1',2 dimethy1indo1-3'-yl)-phthaliderepresented by the following formula CHaNH- was obtained as alight-color former having a melting point of ZOO-202 C. When a benzenesolution of the color former was brought into contact with an acid claylayer coated on a paper, the color former immediately colored violet.

PRODUCTION EXAMPLE 4 5,6,7-tetrachlorophthalide represented by thefollowing formula a I Y O CH3 as a liglit g reen'colori'former having amelting point of 2 51 253. C. Whena benzene solution of the color formerwas brought into' contact -withan acid clay layer coated on paper, thecolor former immediately colored blue.

PRODUCTION EXAMPLE 5 as a white color former having a melting point193l94 C. When a benzene solution of the color former was brought intocontact with an acid; clay layer coated on a paper, the color formerimmediately colored violet-blue.

PRODUCTION EXAMPLE 6 A mixtureof 1.2 g. of1-methyl-2phenyl-3-(2-carboxy- 324f,5',6-tetrabromobenzoyl)-indole, 0.5g. of N,N-diethyl-m-phenetidine, and 5.0 g. of acetic anhydride washeated to 80-85 C. for 3 hours, with stirring, to cause thereaction.Then, the reaction mixture wa treated as in Production Example 1 toprovide 1.1 g. of 3-(2'-ethoxy- 4 diethylaminophenyl) 3 (1'-- methyl 2'phenylindol- 3'-yl)r4,5,6,7-tetrabr0mophthalide represented by thefollowing formula CzHs Cm as'a light-yellow color former having amelting pointof 205206 C. When a benzene solution of the color formerwas brought into contact with an acid clay layer coated on a paper, thecolor former immediately colored blue.

PRODUCTION EXAMPLE 7 .To .15 -g..of..monochlorobenzene were added 2.3 g.of

reaction mixture was treated as in Production Example 3 to provide 1.6g. of 3-(2'-ethoxy-4'-diethylaminophenyl) 3 (2' methylindol 3'yl)-phthalide represented by the following formula CgHs as alight-yellow color former having a melting point of 223-225 C. When abenzene solution of the color former was brought into contact with anacid clay layer coated on a paper, the color former immediately coloredviolet.

PRODUCTION EXAMPLE 8 A mixture of 2.0 g. of 1,2 dimethyl 3 (2'canboxybenzoyl)-indole, 1.2 g. of N-acetyl-N-methyl-m-anisidine, and20.0 g. of acetic anhydride was heated to 90 C. for 2 hours, withstirring, to cause the reaction. The reaction mixture was then treatedas in Production Example 1 to provide 2.0 g. of3-(2'-methoxy-4-N-acetyl-N- methylamino-phenyl) 3 (1',2' dimethylindol3' y1)- phthalide represented by the following formula as a white colorformer having a melting point of 245- 253 C. When a benzene solution ofthe color former was brought into contact with an acid clay layer coatedon a paper, the color former immediately colored violetblue.

PRODUCTION EXAMPLE 9 as a. light-yellow color formerhaving a melting,point of -l97 C. When a benzene solution of the colorformer was broughtinto contact.with an acid. clay layer coated on a paper, the colorformer immediately colored violetblue.

The microcapsules used in the pressure-sensitive copying papers may beformed by any state of the art process used to form oil-containingpressure-sensitive microcapsules, e.g., as described in US.Pats.2,548,366,.2,800,457 or .2,800,458. These processes utilize.,thephenomenon of composite;coacervations.=

The amount of the color. former to be used is generally 0.5-5.0% byweight based on the weight of the-organic solvent described above, suchasethylene glyleol; chlorobenzene, and chlorodiphenyl. However, lesserand greater amounts may be used.

As the electron accepting solid acid, acid clay, attapulgite, zeolite,bentonite, kaolin, acid polymers such as phenolic resin etc. are used.

The pressure-sensitive copying paper of this invention in which thephthalide compound represented by the aforesaid general formula is usedas a color former is colorless or has a very faint yellow characterbefore use, but when the pressure-sensitive copying paper subjected tolocalized pressure by, e.g., handwriting or typewriting, purple or bluecoloring instantly occurs. Moreover, the color density of the color thusformed is high, and the light and water resistance thereof areexcellent.

Furthermore, by using the aforesaid color former together with knownyellow-color formers, red-color formers, blue-color formers, green-colorformers, and the like, a pressure-sensitive copying paper capable ofproviding various colors copying can be obtained unaccompanied by anyadverse effect, such as; desensitization.

The present invention will now be further explained in greater detail bythe following examples.

Example 1 In 100 g. of trichlorodiphenyl there was dissolved 2.5 g. of3-(2-methyl 4'diethylaminophenyl)-3-(1',2'-dimethylindol-3-yl)-phthalide, and then 20g. of gum arabic and 160 g. of water were added to the solution at 50 C.followed by emulsification. To the emulsion were added 20 g. ofacid-treated gelatin and 160 g. of water and thereafter the pH of theemulsion was adjusted to 5 by adding acetic acid while stirring. Then,500 g. of water was added to the system to cause coacervation and toform dense liquid films of gelatin-gum arabic around the oil drops oftrichlorodiphenyl. After adjusting the pH of the system to 4.4, 3.8 g.of aqueous 37% formalin solution was added thereto to harden theaforesaid liquid films. The system was then cooled to C., the pH thereofwas adjusted to 9 by adding an aqueous solution of sodium hydroxide, andthe system was allowed to stand for 5-6 hours, whereby encapsulation wascompleted. The microcapsule-containing liquid was applied to a paper byroll coating or air-knife coating and dried to give a colorless coatedsheet. When the coated paper (upper sheet) was placed on a sheet (lowersheet) having coated thereon a layer of acid clay (an electron acceptiveadsorbent) so that the microcapsule layer was closely brought intocontact with the adsorbent layer and localized pressure was applied byhandwriting or typewriting, the areas of the lower sheet to whichpressure was applied were immediately colored blue.

The color density of the color former thus formed was high. Moreoverwhen the blue color former was placed for an extended period of time ina chamber free from the direct rays of the sun, no discoloring wasobserved. When it was exposed to the direct rays of the sun for anextended period of time, fading was scarcely observed. Furthermore, thecolor former thus colored exhibited excellent water resistance.

On the other hand, when the same procedure as above was followed using aknown color former, 3-(4'-dimethylaminophenyl)-3-( l',2'-dirnethylindol3' yl)-phthalide', disclosed in US. Pat. No. 3,540,911, although thecolor former colored immediately blue-purple on the lower sheet, thecolor density was not high, and the light'and water resistance thereofwas poor.

Example 2 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 1.5 g. of 3- (2'-ethoxy 4'diethylaminophenyl)-3-(1,2'-dimethylindol-3'-yl) phthalide was used asthe color former. When the upper sheet was placed on the lower sheet sothat the microcapsule layer was brought into intimate contact with theacid clay layer of the lower sheet and localized pressure was appliedthereto by handwriting, the areas of the acid clay layer thus pressedimmediately colored violet-blue. Upon testing the violet-blue colorformer for light fastness, it was confirmed that the color former hadsufficient stability for practical use. The violet-blue color formeralso was excellent in water resistance.

Example 3 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 1.5 g. of 3- (2-methoxy- 4methylaminophenyl)-3-(l',2-dimethylindol-3'-yl)-phthalide was used asthe color former. When the upper sheet was placed on the lower sheet sothat the microcapsule layer was brought into intimate contact with theacid clay layer of the under sheet and localized pressure was appliedthereto by handwriting, the areas of the acid clay layer thus pressedimmediately colored violet. By testing the color former thus coloredviolet with respect to light fastness, it was confirmed that the violetcolor former had sufficient stability for practical use.

Example 4 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 1.5 g. of 3- (2-methoxy 4dimethylaminophenyl)-3-(1',2'-dimethylindol-3'-yl)-4,5,6,7-tetrachlorophthalide was used as the colorformer. When the upper sheet was placed on the lower sheet so that themicrocapsule layer was brought into intimate contact with the acid claylayer of the lower sheet and localized pressure was applied thereto byhandwriting, the areas of the acid clay layer thus pressed wereimmediately colored blue. By testing the blue color former with respectto light fastness, it was confirmed that the blue color former hadsuflicient stability for practical use. The blue color former was alsoexcellent in water resistance.

Example 5 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 1.5 g. of 3- (2-ethoxy 4'diethylaminophenyl)-3-(l',2dimethylindol-3-yl)-5-dimethylaminophthalidewas used as the color former. When the upper sheet was placed on thelower sheet so that the microcapsule layer of the upper sheet wasbrought into intimate contact with the acid clay layer of the lowersheet and localized pressure was applied thereto by handwriting, theareas of the acid clay layer thus pressed immediately coloredviolet-blue. By testing the violet-blue color former with respect tolight fastness, it was confirmed that the violet-blue color formervioletblue had sufiicient stability for practical use. The violetbluecolor former was also excellent in water resistance.

Example 6 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 2.0 g. of 3- (2'-ethoxy 4diethylaminophenyl) 3 5 (Imethyl-2'-phenylindol-3'-yl)-4,5,6,7-tetrabromophthalide was used as the colorformer. When the upper sheet was placed on the lower sheet so that themicrocapsule layer of the upper sheet was brought into intimate contactwith the acid clay layer of the lower sheet and localized pressure wasapplied thereto by handwriting, the areas of the acid clay layer thatpressed immediately colored blue. By testing the blue color former withrespect to light fastnes's, it was confirmed that the colored colorformer had sufficient stability for practical use. The colored colorformer also was excellent in water resistance.

" Example 7 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 2.0 g. of3-(2'ethoxy-4'-diethylaminophenyl)-3 (2' methylindol- 3'-yl)-phthalidewas used as the color former. When the upper sheet was placed on thelower sheet so that the microcapsule layer of the upper sheet wasbrought into intimate contact with the acid clay layer of the lowersheet and localized pressure was applied thereto by handwriting, theareas of the acid clay layer thus pressed immediately colored violet. Bytesting the violet color former with respect to light fastness, it wasconfirmed that the colored color former had suflicient stability forpractical use.

Example 8 A colorless upper sheet was prepared following the sameprocedure as in Example 1 except that 2.0 g. of 3 (2' methoxy 4'N-acetyl-N-methylaminophenyl)-3- (1',2'-dimethylindol-3'-yl)-phthalidewas used as the color former. When the upper sheet was placed on thelower sheet so that the microcapsule layer of the upper sheet wasbrought into intimate contact with the acid clay layer of the lowersheet and localized pressure was applied thereto by handwriting, theareas of the acid clay layer thus pressed immediately coloredviolet-blue. By testing the violet-blue color former with respect tolight fastness, it was confirmed that the colored color former hadsulficient stability for practical use.

Example 9 An upper sheet was prepared following the same procedure as inExample 1 except that 0.5 g. of 3-(2'-methoxy- 4 N methyl Nbenzylaminophenyl)-3-(1'-ethyl2'- phenylindol-3'-yl)-phthalide, 0.8 g.of o-hydroxybenzalacetophenone, 0.8 g. of Rhodamine B-Anilino-Lactam,0.2 g. of Crystal Violet Lactone, and 0.2 g. of Malachite Green Lactonewere used as the color formers. When the upper sheet was placed on thelower sheet so that the microcapsule layer was brought into intimatecontact with the acid clay layer of the lower sheet and localizedpressure was applied thereto by handwriting, the areas of the acid claylayer thus pressed immediately colored black. The color thus formed wasvery stable and had excellent light and water resistance.

What is claimed is:

1. A pressure-sensitive copying sheet comprising an adsorbent solid acidand a microencapsulated color former capable of forming a distinct colorwhen reacted with said adsorbent solid acid coated on the same ordifierent surface of support or supports, said microcapsules containingan organic solvent having dissolved therein a phthalide color formercomprising at least one phthalide compound represented by the generalformula wherein R represents a member selected from the group consistingof a hydrogen atom, a methyl group, an ethyl group, an acetyl group anda benzyl group; R represents a member selected from the group consistingof a methyl group and an ethyl group; R represents a member selectedfrom the group consisting of a hydrogen atom,

a methyl group and an ethyl group; R represents a member selected fromthe group consisting of a methyl group and a phenyl group; X representsa member selected from the group consisting of a methyl group, a methoxygroup and an ethoxy group; Y represents a member selected from the groupconsisting of a hydrogen atom, a chlorine atom, a bromine atom and adimethylamino group; and n is an integer from 1 to 4.

2. The pressure-sensitive transfer sheet as claimed in Claim 1 whereinsaid phthalide compound is selected from the group consisting of3-(2-methy1-4'-diethylaminophenyl)-3-(1',2'-dimethylindol-3-yl)-phthalide,

3- 2'-ethoxy-4'-diethylaminophenyl) -3-( 1',2'-dimethylindol-3 '-yl-phthalide,

3- 2-methoxy-4'-methylaminophenyl) -3-( l',2-

dimethyl-indol-3'-yl)-phthalide,

3-(2'-methoxy-4-dimethylaminophenyl)-3-( 1',2-

dimethyl-indol-3 -yl) -4,5 ,6,7-tetrachlorophthalid e, 3-2'-ethoxy-4-diethylaminophenyl) -3-(1,2-dimethylindol-3'-yl)-5-dimethylaminophthalide,3-(2-ethoxy-4'-diethylaminopheny1)-3-( 1 '-methyl-2- phenylindol-3 '-y1)-4,5,6,7-tetrabromophthalide,3-(2'-ethoxy-4'-diethylaminophenyl)-3-(2'-methylindol-3 '-yl -phthalide,3-(2'-methoxy-4-N-acetyl-N-methylaminophenyl)-3-(l',2'-dimethylindol-3'-yl)-phthalide, and 3-(2-methoxy-4'-N-methyl-N-benzylaminophenyl -3 1-ethyl-2-phenylindol-3'-yl -phthalide.

3. The pressure sensitive transfer sheet as claimed in Claim 1 whereinfrom about 0.5 to about 5.0% of said color former is present in saidorganic solvent based on the weight of said organic solvent.

4. The pressure-sensitive transferring sheet as claimed in Claim 1,wherein said microcapsules contain a least one color former in additionto said phthalide color former.

5. The pressure sensitive transfer sheet as claimed in Claim 4, whereinsaid at least one color former is se lected from the group consisting ofo-hydroxybenzalacetophenone, Rhodamine B-anilinolactam, Crystal VioletLactone and Malachite Green Lactone.

References Cited UNITED STATES PATENTS 3,540,911 11/1970 Chao-han Lin1l736.2 3,540,910 11/1970 Chao-han Lin 117-368 3,713,863 1/1973 Chao-hanLin et al. 117-36.8 3,491,112 1/1970 Chao-han Lin l17-36.2 2,505,4864/1950 Green 260343.3 3,244,549 4/1966 Parnham et al. 11736.2 3,268,5378/1966 Gosnell et al. 117-362 3,336,337 8/1967 Gosnell 11736.2 3,455,7217/1969 Phillips et al. 117-36.2 3,491,111 1/1970 Lin 11736.2

WILLIAM D. MARTIN, Primary Examiner W. R. TRENOR, Assistant Examiner US.Cl. X.R.

117-362, L, UA; 260235, 240 G, 343.3

